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TheBackRoads
TheBackRoads Solar Expert Posts: 274 ✭✭
in Off Grid Solar & Battery Systems #1
Hey All,

Dill and I were talking and wondering... "How much hydrogen can a pair of batteries give off when charged at a 10% rate? I'd be curious to know too since ALL of my batteries aren't vented outside." - Dill. I've got mine in a box on the 2nd floor of a house, Dill has his in his garage on a work bench. I'm looking at replacing mine with some new AGM's (currently have AGM) but wondering do they REALLY need to be vented outside? I understand it's always a GOOD idea however. We're talking about a pair or 2 of the T105 size... Thoughts?
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  • BB.
    BB. Super Moderators, Administrators Posts: 33,457 admin
    #2
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    Re: Gas

    I would start with this paper... Assuming a cell is 100% charged, then all of the energy should go into producing hydrogen/oxygen gases (and waste heat.
    A Realistic Approach

    We can begin by supplementing our propane use with hydrogen. The next question is how much hydrogen we can produce. Home Power will soon be adding two trackers to test. With our additional loads, this will add about 1.5 kw-hr surplus power per day. We use the following conversion factors to determine how many cubic feet of hydrogen (at atmospheric pressure) 1.5 kW-hr will produce and how much energy in BTU this amount of hydrogen will give us.

    1cu. ft. H2=0.791 kW-hr or 1 kW-hr=12.6cu. ft. H2 1 cu. ft.=270 BTU Electrolyzer efficiency = 50%

    Using the above conversion factors,

    1.5kW-hr/day x 12.6 cu. ft./kW-hr x .5 eff.=9.45 cu. ft. H2/day. 9.45 cu. ft. H2.x 270 BTU/cu. ft. H2=2551.5 BTU/day.

    We will be able to produce 9.45 cubic feet of hydrogen at atmospheric pressure (or 2550 BTU hydrogen) each day from our 1.5 kW-hr/day surplus energy. This will only run our cookstove burner (assuming 10,000 BTU/hour) for a little more than 15 minutes.

    Or find a high schooler that just took a year of Chem. ;)

    -Bill

    PS: Add the next answer (I guess) to the unasked question:

    http://en.wikipedia.org/wiki/Hydrogen_safety
    [h=3]Mixtures[/h]
    • "The flammability limits based on the volume percent of hydrogen in air at 14.7 psia (1 atm, 101 kPa) are 4.0 and 75.0. The flammability limits based on the volume percent of hydrogen in oxygen at 14.7 psia (1 atm, 101 kPa) are 4.0 and 94.0."
    • "The limits of detonability of hydrogen in air are 18.3 to 59 percent by volume"[4]
    • "Flames in and around a collection of pipes or structures can create turbulence that causes a deflagration to evolve into a detonation, even in the absence of gross confinement."
    (For comparison: Deflagration limit of gasoline in air: 1.4–7.6%; of acetylene in air,[5] 2.5% to 82%)
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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  • Dill
    Dill Solar Expert Posts: 170 ✭✭
    #3
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    Re: Gas

    I know it's a 'just in case' thing but I was just curious if anyone had any info on it. My garage has 4 GC batteries, and gets opened several times a day and isn't air tight anyways (what garage is). Those batteries need water about ever 3 months. The amounts I add is never very much, maybe an ounce or two to each cell. My cabin is only used a half dozen days a month and only has 2 batteries, and these batteries have never needed water since I installed them over 6 months ago.

    I do remember making hydrogen in chem class in high school and filling a balloon with it, and then moving it over top of a beaker. It was a nice, loud pop!
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #4
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    Re: Gas

    Hey, did you ever see those ads for "run your car on hydrogen!" conversions? Also called "HHO" kits or some such? Ever wonder why there is absolutely no chance that they can work?

    Guess what; same thing. The amount of gas produced by the electrolytic action is very small indeed, and hardly a danger (much less able to contribute significantly to running your car).

    Mine are not vented to the outside because such would let more cold air in than hydrogen gas out. This place leaks like a sieve. However in a closed travel trailer, say, I think I'd go AGM's rather than try to vent.
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  • Dill
    Dill Solar Expert Posts: 170 ✭✭
    #5
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    Re: Gas

    glad it seems I have nothing to worry about!
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  • TheBackRoads
    TheBackRoads Solar Expert Posts: 274 ✭✭
    #6
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    Re: Gas

    Boom -- haaaa just kidding dill. Now lets get those panels mounted!!
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #7
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    Re: Gas
    Cariboocoot wrote: »
    Hey, did you ever see those ads for "run your car on hydrogen!" conversions? Also called "HHO" kits or some such?

    They use di-hydrogen monoxide instead of just plain water.
    Also called hydronium hydroxide = (H3O+)(OH-)
    SMA SB 3000, old BP panels.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #8
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    Re: Gas
    inetdog wrote: »
    They use di-hydrogen monoxide instead of just plain water.
    Also called hydronium hydroxide = (H3O+)(OH-)

    Oh that explains it: they use heavy water! The stuff they make the atomic bombs with! No wonder they get so much power! :p
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  • Dill
    Dill Solar Expert Posts: 170 ✭✭
    #9
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    Re: Gas
    TheBackRoads wrote: »
    Boom -- haaaa just kidding dill. Now lets get those panels mounted!!

    picked up the hardware at Fleet Farm during lunch just today!
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  • inetdog
    inetdog Solar Expert Posts: 3,123 ✭✭✭✭
    #10
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    Re: Gas
    Cariboocoot wrote: »
    Oh that explains it: they use heavy water! The stuff they make the atomic bombs with! No wonder they get so much power! :p

    That would actually be deuterium oxide or tritium oxide. Or a mixture.
    Although maybe Cold Fusion is involved too?
    SMA SB 3000, old BP panels.
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  • waynefromnscanada
    waynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    #11
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    Re: Gas

    Problem with burning the "gas" given off by charging batteries, is that it isn't just hydrogen, it's also mixed with oxygen from the batteries - - in the perfect ratio for a real good BANG! Neighbor of mine few years ago got brainwashed over the running a car on alternator produced hydrogen gag. Tried to warn him - - -
    While "playing" with it, trying to make it work, the hydrogen/oxygen mixture ignited from a backfire up through the carburetor, and the whole device blew up in his face. No, he wasn't hurt, but he did have to change his shorts! lol
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #12
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    Re: Gas
    inetdog wrote: »
    That would actually be deuterium oxide or tritium oxide. Or a mixture.
    Although maybe Cold Fusion is involved too?

    Sure! It cold fuses with the gasoline atoms causing a spontaneous release of the hydrogen from the carbon in the molecules with the additional oxidizing of the extra O2 particles which in turn accelerates the energy potential causing a significant power increase with no additional fuel added!

    We could sit around all day making up this drivel - and still not get paid for it.
    Morals are what stand between you and that large fortune you've always dreamed of. :p
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #13
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    Re: Gas

    personally, i wouldn't vent so few of batteries even if they were of the fla type. local codes may say otherwise if applicable. i wouldn't confine them too much either, just in case.
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